The Perfect Cup of Coffee

Refractometer

Refractometers have been in use for a while at wineries and breweries, to measure the sugar in fresh grapes and the progress of the fermentation process in both wine and beer.

The devices measure the refraction of light through a liquid. In recent years, baristas have been using them to brew the “perfect cup of coffee.”

For brewing said perfect cup, two factors come in to play, according to the National Coffee Association: the brew strength, or total dissolved solids (which must be between 1.2 and 1.55 percent), and the brew’s extraction rate. The perfect coffee extracts only between 18 and 22 percent of the flavor from a coffee bean.

A refractometer can be used to determine both those numbers and thus has become the essential tool for baristas the world over.